U.S. patent application number 14/913866 was filed with the patent office on 2016-07-21 for transmission fluid.
This patent application is currently assigned to IDEMITSU KOSAN CO., LTD.. The applicant listed for this patent is IDEMITSU KOSAN CO., LTD.. Invention is credited to Toshiaki IWAI.
Application Number | 20160208192 14/913866 |
Document ID | / |
Family ID | 52628547 |
Filed Date | 2016-07-21 |
United States Patent
Application |
20160208192 |
Kind Code |
A1 |
IWAI; Toshiaki |
July 21, 2016 |
TRANSMISSION FLUID
Abstract
A transmission fluid contains a base oil and calcium carbonate.
The calcium carbonate is dispersed in a form of aggregations in the
transmission fluid. A ratio of the aggregations having a particle
diameter of 200 nm or more is 28 mass % or less in terms of calcium
based on a total amount of the aggregations. A base value of the
transmission fluid is in a range from 0.5 mgKOH/g to 3 mgKOH/g by a
hydrochloric acid method.
Inventors: |
IWAI; Toshiaki;
(Ichihara-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
IDEMITSU KOSAN CO., LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
IDEMITSU KOSAN CO., LTD.
Chiyoda-ku, Tokyo
JP
|
Family ID: |
52628547 |
Appl. No.: |
14/913866 |
Filed: |
September 8, 2014 |
PCT Filed: |
September 8, 2014 |
PCT NO: |
PCT/JP2014/073694 |
371 Date: |
February 23, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10N 2030/06 20130101;
C10N 2020/06 20130101; C10M 125/10 20130101; C10N 2030/02 20130101;
C10N 2040/045 20200501; C10M 2219/046 20130101; C10M 2205/0285
20130101; C10M 169/042 20130101; C10M 159/22 20130101; C10M 105/04
20130101; C10M 169/04 20130101; C10N 2040/042 20200501; C10M
2207/028 20130101; C10M 2207/262 20130101; C10N 2010/04 20130101;
C10N 2030/52 20200501; C10M 159/24 20130101 |
International
Class: |
C10M 169/04 20060101
C10M169/04; C10M 125/10 20060101 C10M125/10; C10M 105/04 20060101
C10M105/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 9, 2013 |
JP |
2013-186766 |
Claims
1. A transmission fluid comprising: a base oil; and calcium
carbonate, wherein the calcium carbonate is dispersed in a form of
aggregations in the transmission fluid, a ratio of the aggregations
having a particle diameter of 200 nm or more is 28 mass % or less
in terms of calcium based on a total amount of the aggregations,
and a base value of the transmission fluid is in a range from 0.5
mgKOH/g to 3 mgKOH/g by a hydrochloric acid method.
2. The transmission fluid according to claim 1, wherein the calcium
carbonate is derived from an overbased organic acid calcium salt
compound, and a content of the calcium carbonate is a range from
0.001 mass % to 0.3 mass % in terms of calcium based on a total
amount of the transmission fluid.
3. The transmission fluid according to claim 2, wherein the
overbased organic acid calcium salt compound is an overbased
detergent, and the overbased detergent is at least one selected
from the group consisting of a sulfonate detergent, a salicylate
detergent and a phenate detergent.
4. The transmission fluid according to claim 1, wherein the base
oil comprises polyalphaolefin.
5. The transmission fluid according to claim 4, wherein a ratio of
the polyalphaolefin in the base oil is 30 mass % or more.
6. The transmission fluid according to claim 4, wherein the
polyalphaolefin has a kinematic viscosity at 100 degrees C. in a
range from 2 mm.sup.2/s to 200 mm.sup.2/s.
7. The transmission fluid according to claim 1, wherein the
transmission fluid has a kinematic viscosity at 100 degrees C. in a
range from 3 mm.sup.2/s to 8 mm.sup.2/s, and the transmission fluid
has a viscosity index of 100 or more.
8. The transmission fluid according to claim 1, wherein the
transmission fluid is suitable for an automatic transmission or a
continuously variable transmission.
Description
TECHNICAL FIELD
[0001] The present invention relates to a transmission fluid.
BACKGROUND ART
[0002] An automatic transmission (AT) is a transmission having a
mechanism in which a transmission torque ratio is automatically set
according to a vehicle speed, a magnitude of load and the like. The
automatic transmission includes a torque converter, gear mechanism,
hydraulic mechanism, wet clutch and the like. Moreover, a
continuously variable transmission (CVT) is also often used as the
transmission. A method of transmitting torque by friction between a
metallic belt or chain and a metallic pulley is well known.
Further, in recent years, an automobile provided with a Dual Clutch
Transmission (DCT) has begun to come on the market. In the DCT that
is a kind of AT, dedicated clutches are respectively prepared in an
odd-numbered stage and an even-numbered stage. Since gears in a
next stage are engaged in advance at gear change, gear change can
be quickly done just by switching the clutches.
[0003] Various transmission fluids usable for the above various
transmissions have been proposed. Particularly, a transmission
fluid having a high kinematic friction coefficient (0) is required
in order to increase a transmission torque volume. For instance,
Patent Literature 1 discloses a lubricating oil composition that
contains a lubricating base oil, polyol compound, alkali metal
borate, ashless dispersant and alkaline earth metal sulfonate. This
composition can further enhance the kinematic friction coefficient
(.mu.d) of the wet clutch (see paragraph [0073] [Advantages of the
Invention]).
CITATION LIST
Patent Literature(s)
[0004] Patent Literature 1: JP-A-2005-8695
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0005] In all of the above AT, CVT and DCT, with longer use of the
transmission fluid, the kinematic friction coefficient (.mu.d) of
the transmission fluid is decreased and vibration (shudder) of an
entire vehicle body caused by stick-slip vibration of a clutch
sliding portion is more likely to occur. Accordingly, a longer
clutch lifetime, specifically, a longer shudder lifetime is
demanded in practical use.
[0006] However, even the above transmission fluid disclosed in
Patent Literature 1 is not always sufficient for maintaining the
kinematic friction coefficient (.mu.d) after the longtime use of
the transmission fluid. In addition, the transmission fluid has a
complicated structure, which entails a high production cost.
[0007] An object of the invention is to provide a transmission
fluid capable of maintaining a high kinematic friction coefficient
(.mu.d) for a long time and providing a long clutch lifetime with a
simple structure.
Means for Solving the Problems
[0008] In order to solve the above problem, the following
transmission fluid is provided according to an aspect of the
invention.
[0009] According to the aspect of the invention, a transmission
fluid contains: a base oil; and calcium carbonate, in which the
calcium carbonate is dispersed in a form of aggregations in the
transmission fluid, a ratio of the aggregations having a particle
diameter of 200 nm or more is 28 mass % or less in terms of calcium
based on a total amount of the aggregations, and a base value of
the transmission fluid is in a range from 0.5 mgKOH/g to 3 mgKOH/g
by a hydrochloric acid method.
[0010] According to the above aspect of the invention, a
transmission fluid capable of maintaining a high kinematic friction
coefficient (.mu.d) for a long time and providing a long clutch
lifetime with a simple structure can be provided.
DESCRIPTION OF EMBODIMENT(S)
[0011] In an exemplary embodiment of the invention, a transmission
fluid is obtained by blending a base oil with calcium carbonate, in
which the calcium carbonate is dispersed in a form of aggregations
in the transmission fluid, a ratio of the aggregations having a
particle diameter of 200 nm or more is 28 mass % or less in terms
of calcium based on a total amount of the aggregations, and a base
value of the transmission fluid is in a range from 0.5 mgKOH/g to 3
mgKOH/g by a hydrochloric acid method. The transmission fluid of
the invention (hereinafter, also referred to as "the present
transmission fluid") will be described in detail below. Herein, the
transmission fluid obtained by blending a base oil and calcium
carbonate means not only a transmission fluid containing the base
oil and calcium carbonate, but also a composition containing a
modified substance obtained by modifying at least one of the base
oil and calcium carbonate, and a composition containing a reactant
obtained by reaction of the base oil and/or calcium carbonate.
[0012] The base oil usable in the present transmission fluid is not
particularly limited, but may be at least one of the mineral oil
and the synthetic oil. Specifically, the base oil may be one or a
plurality of the mineral oil, one or a plurality of the synthetic
oil, or a combination of the mineral oil and the synthetic oil.
[0013] The mineral oil and the synthetic oil are not specifically
limited, but any mineral and any synthetic oil generally usable as
a base oil for a transmission are suitable. Particularly, the base
oil having a kinematic viscosity at 100 degrees C. in a range from
1 mm.sup.2/S to 50 mm.sup.2/s, particularly from 2 mm.sup.2/s to 15
mm.sup.2/s is preferably usable. When the kinematic viscosity at
100 degrees of the base oil is 1 mm.sup.2/s or more, an increase in
abrasion at a sliding portion such as a gear bearing and a clutch
of the transmission is restrained. When the kinematic viscosity at
100 degrees of the base oil is 50 mm.sup.2/s or less, deterioration
of a low-temperature viscosity is expected to be restrained.
[0014] A pour point of the base oil, which is an index of a
low-temperature fluidity, is not particularly limited, but is
preferably minus 10 degrees C. or less, particularly preferably
minus 15 degrees C. or less.
[0015] Further, although not particularly limited, the base oil
preferably has a saturated hydrocarbon component of 90 mass % or
more, a sulfur content of 0.03 mass % or less and a viscosity index
of 100 or more. When the saturated hydrocarbon component is 90 mass
% or more, an amount of deteriorated products is reducible. When
the sulfur content is 0.03 mass % or less, an amount of
deteriorated products is reducible. When the viscosity index of the
base oil is 100 or more, abrasion at a high temperature is
reducible.
[0016] Examples of the mineral oil include a naphthenic mineral
oil, a paraffinic mineral oil and GTL WAX. Specific examples of the
mineral oil include light neutral oil, intermediate neutral oil,
heavy neutral oil, and bright stock, which are obtainable by
solvent purification or hydrogenation purification.
[0017] On the other hand, examples of the synthetic oil include
polybutene, a hydride thereof, polyalphaolefin (e.g., 1-octene
oligomer, 1-decene oligomer), alkylbenzene, polyolester, diacid
ester, polyoxyalkyleneglycol, polyoxyalkyleneglycolester,
polyoxyalkyleneglycolether, hindered ester and silicone oil.
[0018] In the above base oil, it is preferable to blend (mix)
polyalphaolefin (PAO) in use in order to efficiently achieve the
advantages of the invention. Examples of PAO include alphaolefin
homopolymers and alphaolefin copolymers. A ratio of PAO is
preferably 30 mass % or more in the base oil, preferably 50 mass %
or more. A kinematic viscosity at 100 degrees C. of PAO is
preferably in a range from 2 mm.sup.2/s to 200 mm.sup.2/s.
[0019] The present transmission fluid contains calcium carbonate in
a specific form (hereinafter, also referred to as "the present
calcium carbonate"). The present calcium carbonate is dispersed in
a form of aggregations in the transmission fluid. Among the
aggregations, a ratio of an aggregation having a particle diameter
of 200 nm or more (hereinafter, also referred to as a "large
particle") is 28 mass % or less in terms of calcium based on a
total amount of the aggregations, preferably 25 mass % or less.
When the ratio of the large particle in the aggregations is 28 mass
% or less, a resultant transmission fluid can maintain a high
kinematic friction coefficient (.mu.d) for a long time.
[0020] An average particle diameter of the above aggregations is
preferably in a range from 1 nm to 180 nm, more preferably from 10
nm to 150 nm in order to efficiently achieve the advantages of the
invention.
[0021] The particle diameter, a particle-diameter distribution and
the average particle diameter of the above aggregations are
measurable according to electrophoretic light scattering. For
instance, a particle-diameter measurement system using ELSZ-1000S
manufactured by Otsuka Electronics Co., Ltd. is suitably
usable.
[0022] In order to obtain the transmission fluid containing the
present calcium carbonate and the base oil, in which a
predetermined amount of large particles are dispersed in the
transmission fluid, for instance, the base oil or any transmission
fluid may be blended with calcium carbonate having an aggregations
with a predetermined particle size distribution or may be blended
with an overbased organic acid calcium salt compound including a
predetermined aggregation (e.g., an overbased detergent). In the
latter case, the present calcium carbonate is derived from the
overbased organic acid calcium salt compound. A manufacturing
method of calcium carbonate (aggregations) is not particularly
limited, but, for instance, may include neutralizing an organic
acid with basic calcium oxide and hydroxide and subsequently
carbonating excessive basic calcium oxide and hydroxide.
[0023] A content of the present calcium carbonate is preferably in
a range from 0.001 mass % to 0.3 mass % in terms of calcium based
on a total amount of the present transmission fluid, more
preferably from 0.001 mass % to 0.2 mass %, further preferably from
0.01 mass % to 0.2 mass %. When the content of the present calcium
carbonate falls within the above range, a high kinematic friction
coefficient (.mu.d) can be maintained for a long time.
[0024] The ratio of the large particles in the present transmission
fluid is preferably 0.056 mass % or less in terms of calcium based
on the total amount of the present transmission fluid, more
preferably from 0.045 mass % or less. When the ratio of the large
particle in the present transmission fluid falls within the above
range, a high kinematic friction coefficient (.mu.d) can be
maintained for a long time.
[0025] Among the above-described overbased organic acid calcium
salt compound, the overbased detergent is preferably at least one
of a sulfonate detergent, a salicylate detergent and a phenate
detergent in order to efficiently achieve the advantages of the
invention.
[0026] A base value of the present transmission oil is in a range
from 0.5 mgKOH/g to 3 mgKOH/g by a hydrochloric acid method (JIS
K2501), more preferably in a range from 0.7 mgKOH/g to 2.8 mgKOH/g.
When the base value falls within the above range, a high kinematic
friction coefficient (.mu.d) can be maintained for a long time.
[0027] The overbased organic acid calcium salt compound (overbased
detergent) itself only needs to contain calcium carbonate and be
overbased. The base value of the overbased organic acid calcium
salt compound is not particularly limited, but a total base value
thereof is preferably in a range from 10 mgKOH/g to 400 mgKOH/g by
the hydrochloric acid method (JIS K2501).
[0028] The present transmission fluid preferably has the kinematic
viscosity at 100 degrees C. in a range from 3 mm.sup.2/s to 8
mm.sup.2/s, more preferably in a range from 4 mm.sup.2/s to 7
mm.sup.2/s in order to efficiently achieve the advantages of the
invention. A viscosity index of the present transmission fluid is
preferably 100 or more.
[0029] The present transmission fluid can contain various additives
as long as an object of the invention is not hampered. Examples of
the additives usable as needed include a viscosity index improver,
an antioxidant, a antiwear agent, a friction modifier, an ashless
dispersant, a metal deactivator, a rust inhibitor an antifoaming
agent, a pour point depressant, a surfactant and a coloring
agent.
[0030] Examples of the viscosity index improver include
polymethacrylate, dispersed polymethacrylate, olefin copolymer
(e.g. ethylene-propylene copolymer), dispersed olefin copolymer and
styrene copolymer (e.g. styrene-diene copolymer and
styrene-isoprene copolymer). A content of the viscosity index
improver is approximately in a range from 0.5 mass % to 15 mass %
of the total amount of the present transmission fluid in view of
the blending effect thereof.
[0031] An example of the pour point depressant is polymethacrylate
having a mass average molecular weight of 10000 to 150000. A
preferable content of the pour point depressant is approximately in
a range from 0.01 mass % to 10 mass % of the total amount of the
present transmission fluid.
[0032] Examples of the antioxidant include an aminic antioxidant, a
phenolic antioxidant and a sulfuric antioxidant.
[0033] Examples of the aminic antioxidant may include
monoalkyldiphenylamine compounds such as monooctyldiphenylamine and
monononyldiphenylamine; dialkyldiphenylamine compounds such as
4,4'-dibutyldiphenylamine, 4,4'-dipentyldiphenylamine,
4,4'-dihexyldiphenylamine, 4,4'-diheptyldiphenylamine,
4,4'-dioctyldiphenylamine and 4,4'-dinonyldiphenylamine;
polyalkyldiphenylamine compounds such as tetrabutyldiphenylamine,
tetrahexyldiphenylamine, tetraoctyldiphenylamine and
tetranonyldiphenylamine; and naphthylamine compounds such as
alpha-naphthylamine, phenyl-alpha-naphthylamine,
butylphenyl-alpha-naphthylamine, pentylphenyl-alpha-naphthylamine,
hexylphenyl-alpha-naphthylamine, heptylphenyl-alpha-naphthylamine,
octylphenyl-alpha-naphthylamine and
nonylphenyl-alpha-naphthylamine. Particularly, the compounds having
the alkyl group having 4 to 24 carbon atoms, particularly
preferably 6 to 18 carbon atoms are usable. One of the aminic
antioxidant as described above may be used alone or two or more
thereof may be used in combination.
[0034] Examples of the phenolic antioxidant may include
2,6-di-t-butylphenol, 2,6-di-t-butyl-4-methylphenol,
4,4'-methylenebis(2,6-di-t-butylphenol),
4,4'-butylidenebis(3-methyl-6-t-butylphenol),
2,2'-methylenebis(4-ethyl-6-t-butylphenol),
2,2'-methylenebis(4-methyl-6-t-butylphenol), 4,4'-isopropylidene
bisphenol, 2,4-dimethyl-6-t-butylphenol,
tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane,
1,1,3-tris(2-methyl-4-hydroxy5-t-butylphenyl)butane,
1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene,
and 2,6-di-t-butyl-4-ethylphenol.
[0035] Examples of the sulfuric antioxidant may include
dialkylthiodipropionate, dialkylthiocarbamic acid derivative
(except for a metal salt),
bis(3,5-di-t-butyl-4-hydroxybenzyl)sulfide, mercaptobenzothiazole,
a reactant of phosphorus pentasulfide and an olefin, and dicetyl
sulfide.
[0036] One of various antioxidants as described above may be used
alone or two or more thereof may be used in combination.
Particularly, the aminic antioxidant, the phenolic antioxidant or
zinc alkyldithio phosphate is preferably used. A preferable content
of the antioxidant is approximately in a range from 0.05 mass % to
3 mass % of the total amount of the present transmission fluid.
[0037] Examples of the antiwear agent may include a thiophosphoric
acid metal salt (e.g., Zn, Pb and Sb), a thiocarbamic acid metal
salt (e.g., Zn), a sulfur compound, phosphate ester (tricresyl
phosphate) and phosphite ester. A preferable content of the
antiwear agent is approximately in a range from 0.05 mass % to 5
mass % of the total amount of the present transmission fluid.
[0038] Examples of the friction modifier may include a polyhydric
alcohol partial ester such as neopentyl glycol monolaurate,
trimethyrol propanemonolaurate, glycerin monooleate (oleic acid
monoglyceride). A preferable content of the friction modifier is
approximately in a range from 0.05 mass % to 4 mass % of the total
amount of the present transmission fluid.
[0039] Examples of the ashless dispersant may include succinimides,
boron-containing succinimides, benzylamines, boron-containing
benzylamines, succinic acid esters, and mono- or di-carboxylic acid
amides respectively represented by a fatty acid or succinic acid. A
preferable content of the ashless dispersant is approximately in a
range from 0.1 mass % to 20 mass % of the total amount of the
present transmission fluid.
[0040] One of the metal deactivators such as benzotriazole and
thiadiazole may be used alone or two or more thereof may be used in
a combination. A preferable content of the metal deactivator is
approximately in a range from 0.01 mass % to 5 mass % of the total
amount of the present transmission fluid.
[0041] Examples of the rust inhibitor may include a fatty acid,
alkenylsuccinic acid half ester, fatty acid soap, alkyl sulfonate,
fatty acid ester of polyhydric alcohol, fatty acid amide, oxidized
paraffin and alkyl polyoxyethylene ether. A preferable content of
the rust inhibitor is approximately in a range from 0.01 mass % to
3 mass % of the total amount of the present transmission fluid.
[0042] One of the antifoaming agents such as a silicone compound
and an ester compound may be used alone or two or more thereof may
be used in a combination. A preferable content of the antifoaming
agent is approximately in a range from 0.05 mass % to 5 mass % of
the total amount of the present transmission fluid.
[0043] The pour point depressant is exemplified by
polymethacrylate. A preferable content of the pour point depressant
is approximately in a range from 0.01 mass % to 10 mass % of the
total amount of the present transmission fluid.
[0044] The surfactant is exemplified by polyoxyethylene alkyl
phenyl ether. A preferable content of the surfactant is
approximately in a range from 0.01 mass % to 10 mass % of the total
amount of the present transmission fluid.
[0045] The present transmission fluid as described above provides a
long clutch lifetime since the present transmission fluid can
maintain a high kinematic friction coefficient (.mu.d) for a long
time, and is suitably applicable to various transmissions such as
an automatic transmission (AT), a continuously variable
transmission (CV) and a dual clutch (DCT).
EXAMPLES
[0046] Next, the invention will be described in more detail with
reference to Examples and Comparatives. It should be noted that the
invention is not limited to description of the examples and the
like.
Example 1 and Comparatives 1 to 2
[0047] PAO (a kinematic viscosity at 100 degrees C. of 4.0
mm.sup.2/s) was used as the base oil. An overbased calcium
sulfonate having properties shown in Table 1 was blended at 0.15
mass % in terms of calcium based on a total amount of each of the
sample oils to prepare sample oils respectively having properties
shown in Table 1 (all the sample oils are intended to be used for
the transmission). The viscosity index of each of the sample oils
in Example 1 and Comparatives 1 and 2 was 120.
[0048] The overbased calcium was dispersed in the base oil and
checked in terms of a structure of the aggregations. Specifically,
a dispersed state of the aggregations (including large particles)
in each of the sample oils was measured by ELSZ-1000S manufactured
by Otsuka Electronics Co., Ltd. A ratio (mass % relative to the
aggregations) of the large particles in the aggregations formed of
calcium carbonate and an average particle diameter of each of the
large particles were calculated. The results are shown in Table 1.
Average particle diameters of the sample oils were respectively 100
nm in Example 1, 200 nm in Comparative 1 and 800 nm in Comparative
2.
TABLE-US-00001 TABLE 1 Sample Oil Kinematic Base value by Calcium
Carbonate viscosity at hydrochloric Rate of large Sample Oil
100.degree. C. acid method particles Test time (hr) and Kinematic
friction coefficient (.mu.d) (mm.sup.2/s) (mgKOH/g) (mass %) 0 1 6
12 24 48 72 96 120 Ex. 1 4 1.39 23 0.123 0.127 0.127 0.127 0.130
0.131 0.132 0.135 0.134 Comp. 1 4 3.90 40 0.122 0.121 0.125 0.130
0.118 0.138 0.111 0.085 0.048 Comp. 2 4 1.07 73 0.102 0.129 0.143
0.149 0.145 0.150 0.143 0.049 0.009
Evaluation Method
[0049] A kinematic friction coefficient of each of the sample oils
was measured under the following test conditions using an LVFA
friction tester in accordance with JASO M349-2001. The results are
shown in Table 1.
[0050] Material: a cellulose clutch material used in an actual
transmission
[0051] Face Pressure: 1.0 MPa
[0052] Oil Temperature: 120 degrees C.
[0053] Rotation Speed: 150 rpm
Evaluation Results
[0054] As is understood from the results shown in Table 1, the
sample oil of Example 1 containing substantially no large particle
(aggregations having a particle diameter of 200 nm or more) can
maintain a high kinematic friction coefficient (.mu.d) for a long
time and provide a long clutch lifetime (shudder lifetime). On the
other hand, in the sample oils of Comparatives 1 and 2 having a lot
of large particles, although the sample oils having an
approximately equivalent content of overbased calcium sulfonate and
an approximately equivalent base value, the kinematic friction
coefficient (.mu.d) is significantly decreased approximately after
the elapse of 72 hours after the test starts. Accordingly, it is
understood that the decrease in the large particles in the
transmission fluid is crucial.
* * * * *